CMOS Image Sensors

An image sensor is a device that converts a visual image to an electric signal, which is used mostly in digital cameras and other imaging devices. It is a set of charge-coupled device (CCD) or active-pixel sensors (APS) like CMOS sensors. The pixel responds to the light by accumulating charges - the more light, the more charge. Thereby the optical signal is transformed into an electric signal, which gets converted into digial information. Compared to CCD, CMOS sensors are faster, smaller, and cheaper as they are more integrated, which makes them also more power efficient.

In several process flows, the completed CIS wafers get initially bonded onto a glass wafer for subsequent silicon thinning and back-side processing. This glass wafer can act as optical filter and is frequently bonded with patterned adhesive frames as an intermediate layer to avoid adhesive contact of the active pixel area. Several techniques like TSV (through silicon via) exist to feed the electrical contacts from the active front side to the back-side of the device.EV Group provides the equipment for adhesive application (spin and spray coating), patterning (optical lithography) and mechanically aligned or optically aligned bonding. Both thermally and UV curable adhesives are supported.